x86: Access the VGA ROM when needed

Add code to the generic pci_rom file to access the VGA ROM in PCI space
when needed.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/pci/pci_rom.c b/drivers/pci/pci_rom.c
index a16e99f..eb76591 100644
--- a/drivers/pci/pci_rom.c
+++ b/drivers/pci/pci_rom.c
@@ -81,7 +81,12 @@
 #ifdef CONFIG_X86_OPTION_ROM_ADDR
 	rom_address = CONFIG_X86_OPTION_ROM_ADDR;
 #else
-	pci_write_config_dword(dev, PCI_ROM_ADDRESS, (u32)PCI_ROM_ADDRESS_MASK);
+
+	if (pciauto_setup_rom(pci_bus_to_hose(PCI_BUS(dev)), dev)) {
+		debug("Cannot find option ROM\n");
+		return -ENOENT;
+	}
+
 	pci_read_config_dword(dev, PCI_ROM_ADDRESS, &rom_address);
 	if (rom_address == 0x00000000 || rom_address == 0xffffffff) {
 		debug("%s: rom_address=%x\n", __func__, rom_address);